netibios name len

Christopher R. Hertel crh at
Thu Nov 21 17:58:01 GMT 2002

On Fri, Nov 22, 2002 at 04:08:07AM +1030, Richard Sharpe wrote:
> On Thu, 21 Nov 2002, Christopher R. Hertel wrote:
> > On Thu, Nov 21, 2002 at 03:17:05PM +0100, Paolo Abeni wrote:
> > > hi there,
> > > 
> > > I had some troubles while configuring a samba printer. The "host"
> > > component of the netbios resource name was longer than 15 bytes and my
> > > smbclient (version 2.2.5) truncates the netbois host name at that
> > > length.
> > 
> > NetBIOS names are 16 bytes maximum, and Microsoft reserves the 16th byte 
> > for special use.
> Hmmm, this makes it sound like Microsoft has some sort of evil intentions 
> :-)
> When IBM (Barry Feigenbaum) designed the protocol back in '84, the 16th 
> byte was reserved as a type byte then.

Some notes on this:

- I know that Barry Feigenbaum developed the SMB (originally BAF)  
  protocol.  I had not heard that he was also responsible for NetBIOS 
  (though it certainly seems plausible).

- I have found contradictory information regarding IBM's use of the 16th
  byte.  Some sources show no indication that it was 'reserved', others
  (mostly secondary sources) say that it was.

- The RFCs, published in 1987, make no mention of the 16th byte being 

- The suffix byte value used to indicate the SMB Server Service is <20>.
  That's a space--the *same* character used as padding.  So, a name padded 
  to 16 bytes would be the same as a name padded to 15 bytes with a type
  byte of <20>.

- To my knowledge, the vast majority (though clearly not all) of the
  defined NetBIOS suffix byte values in use today are Microsoft's fault.
  It could be, however, that those are the only documented ones.

- As to Microsoft having evil intentions, I think that's just well-earned 
  paranoia on your part.  :)  :)  :)

Thus my statement that Microsoft reserves the 16th byte.  At present, 
they're in charge.  The evidence I have available to me is unclear 
regarding the status of that byte back in the early 80's, but in my book 
I've written that it was likely a practice initiated by IBM.

Captain Pedantic -)-----

Samba Team --     -)-----   Christopher R. Hertel
jCIFS Team --   -)-----   ubiqx development, uninq.
ubiqx Team --     -)-----   crh at
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